sim: Add Observer #628
sim: Add Observer #628
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Adds an Observer interface to the simulator, allowing arbitrary code to receive values from the simulation. The implementation is based on the implementation of write_vcd. An obvious next step would be to make _VCDWriter a subclass of Observer, then - rewrite Simulator.write_vcd() as a call to Simulator.oberve() - remove PySimEngine._vcd_writers and associated code. This commit is an RFC for amaranth-lang#327. It is not intended to be submitted as-is.
Codecov Report
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## master #628 +/- ##
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- Coverage 81.46% 81.25% -0.22%
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Files 49 49
Lines 6446 6475 +29
Branches 1287 1291 +4
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+ Hits 5251 5261 +10
- Misses 1008 1025 +17
- Partials 187 189 +2
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Adds an 'observe' action to cli.py, to go along with generate and
simulate.
This is not intended to be merged. Its purpose is to illustrate the
Observer proposed in the previous change,
Example use:
$ python examples/basic/ctr.py observe -c 3
Simluation begins at 0.0
0.0
o: 1
0.5
o: 0
v: 0
clk: 1
1.0
clk: 0
1.5
v: 1
clk: 1
2.0
clk: 0
2.5
v: 2
clk: 1
Simluation ends at 3.0
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I think this interface isn't appropriate for larger designs (especially ones too large to simulate with the Python simulator and which require CXXRTL). Since a Python function is called for every single value change, it is inevitable that (in cases other than full design waveform capture) most of the calls will be for naught, and a new, more efficient interface would be added later. Even in the case of waveform capture, it's pretty common for full design VCD files to end up being too large, with only a subset being captured. As such I'm closing this PR. Any implementation improving on it needs to be able to observe only a subset of value changes. |
Adds an Observer interface to the simulator, allowing arbitrary code
to receive values from the simulation.
The implementation is based on the implementation of write_vcd. An
obvious next step would be to make _VCDWriter a subclass of Observer,
then
This commit is an RFC for #327.
It is not intended to be submitted as-is.